Reactivity mapping

ABSTRACT

Reactivity mapping methods are provided. A method may include: analyzing each of a group of inorganic particles to generate data about physical and/or chemical properties of the inorganic particles; and generating correlations between the properties of inorganic particles based on the data.

BACKGROUND

In well cementing, such as well construction and remedial cementing,cement compositions are commonly utilized. Cement compositions may beused in a variety of subterranean applications. For example, insubterranean well construction, a pipe string (e.g., casing, liners,expandable tubulars, etc.) may be run into a well bore and cemented inplace. The process of cementing the pipe string in place is commonlyreferred to as “primary cementing.” In a typical primary cementingmethod, a cement composition may be pumped into an annulus between thewalls of the well bore and the exterior surface of the pipe stringdisposed therein. The cement composition may set in the annular space,thereby forming an annular sheath of hardened, substantially impermeablecement (i.e., a cement sheath) that may support and position the pipestring in the well bore and may bond the exterior surface of the pipestring to the subterranean formation. Among other things, the cementsheath surrounding the pipe string functions to prevent the migration offluids in the annulus, as well as protecting the pipe string fromcorrosion. Cement compositions also may be used in remedial cementingmethods, for example, to seal cracks or holes in pipe strings or cementsheaths, to seal highly permeable formation zones or fractures, to placea cement plug, and the like.

A particular challenge in well cementing is the development ofsatisfactory mechanical properties in a cement composition within areasonable time period after placement in the subterranean formation.Oftentimes several cement compositions with varying additives are testedto see if they meet the material engineering requirements for aparticular well. The process of selecting the components of the cementcomposition are usually done by a best guess approach by utilizingprevious slurries and modifying them until a satisfactory solution isreached. The process may be time consuming and the resulting slurry maybe expensive. Furthermore, the cement components available in any oneparticular region may vary in composition from those of another regionthereby further complicating the process of selecting a correct slurry.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe present invention, and should not be used to limit or define theinvention.

FIG. 1 is a chart showing simulated results for compressive strengthindex calculations.

FIG. 2 is a chart showing simulated results for compressive strengthindex calculations.

FIG. 3 is a schematic illustration of an example system for analyzingcement components.

FIG. 4 is a schematic illustration of an example system for generatingcement compositions.

FIG. 5 is a schematic illustration of showing introduction of a cementcomposition into a wellbore.

DETAILED DESCRIPTION

The present disclosure may generally relate to cementing methods andsystem. Provided herein are methods that may include identifying andcategorizing silica sources, cements, and other materials based onphysicochemical properties. In some examples, the silica sources may beconsidered inorganic particles. The inorganic particles may or may notcomprise silica and may comprise other minerals such as alumina andother oxides. The physicochemical properties of each cement component ofa cement composition may affect the final set mechanical properties ofthe slurry as well as the dynamic or time based properties such asmixability, rheology, viscosity, and others. Every cement component mayaffect one or more of the properties mentioned, sometimes unpredictably.For example, a locally sourced fly ash may be added to a cementcomposition. The added fly ash may increase the compressive strength ofthe cement composition and may have no effect on for example, thethickening time of the cement composition. In another region, a locallysourced fly ash may also increase the compressive strength of the cementcomposition but may also increase the thickening time. The unpredictablebehavior of a cement composition may not be realized until multiple labtests have been performed.

The cement compositions generally may comprise water and a cementadditive. The cement additive may comprise two or more cementcomponents, which may be dry blended to form the cement additive priorto combination with the water. Alternatively, the cement components maynot be combined until mixture with the water. The cement components maygenerally be described as alkali soluble.

The cement components may also be cementitious in nature. A cementcomposition may comprise water and a cement additive, such as, hydrauliccement, cement kiln dust, and/or a natural pozzolan, among others. Asdescribed in more detail herein, the cement compositions may be foamedand/or extended as desired by those of ordinary skill in the art.

The cement compositions may have a density suitable for a particularapplication. The cement compositions may have any suitable density,including, but not limited to, in the range of about 8 pounds per gallon(“ppg”) to about 16 ppg (1 g/cm³ to 1.9 g/cm³). In the foamed examples,the cement compositions may have a density in the range of about 8 ppgto about 13 ppg (1 g/cm³ to 1.6 g/cm³) (or even lower).

The water used in the cement compositions may include, for example,freshwater, saltwater (e.g., water containing one or more saltsdissolved therein), brine (e.g., saturated saltwater produced fromsubterranean formations), seawater, or combinations thereof. Generally,the water may be from any source, provided that it does not contain anexcess of compounds that may undesirably affect other components in thecement composition. The water may be included in an amount sufficient toform a pumpable slurry. The water may be included in the cementcompositions in any suitable range, including, but not limited to, inthe range of about 40% to about 200% by weight of the cement additive(“bwoc”). In some examples, the water may be included in an amount inthe range of about 40% to about 150% bwoc.

The cement additive may comprise two or more cement components. One ofthe cement components may comprise a hydraulic cement. A variety ofhydraulic cements may be utilized in accordance with the presentdisclosure, including, but not limited to, those comprising calcium,aluminum, silicon, oxygen, iron, and/or sulfur, which set and harden byreaction with water. Suitable hydraulic cements may include Portlandcements, gypsum, and high alumina content cements, among others.Portland cements that are suited for use in the present disclosure maybe classified as Classes A, C, G, and H cements according to AmericanPetroleum Institute, API Specification for Materials and Testing forWell Cements, API Specification 10, Fifth Ed., Jul. 1, 1990. Inaddition, in some examples, cements suitable for use in the presentinvention may be classified as ASTM Type I, II, or III. Cementcompositions that may be considered “low Portland” may be designed byuse of the techniques disclosed herein.

Where present, the hydraulic cement generally may be included in thecement compositions in an amount sufficient to provide the desiredcompressive strength, density, and/or cost. The hydraulic cement may bepresent in the cement compositions in any suitable amount, including,but not limited to, in the range of about 0% to about 99% bwoc. In someexamples the hydraulic cement may be present in an amount rangingbetween any of and/or including any of about 1%, about 5%, about 10%,about 20%, about 40%, about 60%, about 80%, or about 90% bwoc. Cementcomposition that are considered “low Portland” may be used, in that thePortland cement (where used) may be present in the cement composition inan amount of about 40% or less bwoc and, alternatively, about 10% orless. In addition, the cement compositions may also be designed that arefree (or essentially free) of Portland cement. Those of ordinary skillin the art, with the benefit of this disclosure, should be able toselect an appropriate amount of hydraulic cement for a particularapplication.

In addition to Portland cement, additional cement components may be usedthat can be considered alkali soluble. A cement component is consideredalkali soluble where it is at least partially soluble in an aqueoussolution of pH 7.0 or greater. Certain of the alkali soluble cementcomponents may comprise a geopolymer cement, which may comprise analuminosilicate source, a metal silicate source, and an activator. Thegeopolymer cement may react to form a geopolymer. A geopolymer is aninorganic polymer that forms long-range, covalently bonded,non-crystalline networks. Geopolymers may be formed by chemicaldissolution and subsequent re-condensation of various aluminosilicatesand silicates to form a 3D-network or three-dimensional mineral polymer.

The activator for the geopolymer cement may include, but is not limitedto, metal hydroxides chloride salts such as KCl, CaCl₂, NaCl, carbonatessuch as Na₂CO₃, silicates such as sodium silicate, aluminates such assodium aluminate, and ammonium hydroxide.

The aluminosilicate source for the geopolymer cement may comprise anysuitable aluminosilicate. Aluminosilicate is a mineral comprisingaluminum, silicon, and oxygen, plus counter-cations. There arepotentially hundreds of suitable minerals that may be an aluminosilicatesource in that they may comprise aluminosilicate minerals. Eachaluminosilicate source may potentially be used in a particular case ifthe specific properties, such as composition, may be known. Someminerals such as andalusite, kyanite, and sillimanite are naturallyoccurring aluminosilicate sources that have the same composition,Al₂SiO₅, but differ in crystal structure. Each mineral andalusite,kyanite, or sillimanite may react more or less quickly and to differentextents at the same temperature and pressure due to the differingcrystal structures. Other suitable aluminosilicate sources may include,but are not limited to, calcined clays, partially calcined clays,kaolinite clays, lateritic clays, illite clays, volcanic rocks, minetailings, blast furnace slag, and coal fly ash.

The metal silicate source may comprise any suitable metal silicate. Asilicate is a compound containing an anionic silicon compound. Someexamples of a silicate include the orthosilicate anion also known assilicon tetroxide anion, SiO₄ ⁴⁻ as well as hexafluorosilicate [SiF₆]²⁻.Other common silicates include cyclic and single chain silicates whichmay have the general formula [SiO_(2+n)]^(2n−) and sheet-formingsilicates ([SiO_(2.5)]⁻)_(n). Each silicate example may have one or moremetal cations associated with each silicate molecule. Some suitablemetal silicate sources and may include, without limitation, sodiumsilicate, magnesium silicate, and potassium silicate.

Where present, the geopolymer cement generally may be included in thecement compositions in an amount sufficient to provide the desiredcompressive strength, density, and/or cost. The geopolymer cement may bepresent in the cement compositions in any suitable amount, including,but not limited to, an amount in the range of about 0% to about 99%bwoc. In some examples the geopolymer cement may be present in an amountranging between any of and/or including any of about 1%, about 5%, about10%, about 20%, about 40%, about 60%, about 80%, or about 90% bwoc.Those of ordinary skill in the art, with the benefit of this disclosure,should be able to select an appropriate amount of geopolymer cement fora particular application.

Additional cement components that are alkali soluble may be considered asilica source. As used herein, silica has the plain and ordinary meaningof silicon dioxide (SiO₂). By inclusion of the silica source, adifferent path may be used to arrive at a similar product as fromPortland cement. For example, a pozzolanic reaction may be inducedwherein silicic acid (H₄SiO₄) and portlandite (Ca(OH)₂ react to form acement product (calcium silicate hydrate). If other compounds, such as,aluminate, are present in the silica source, additional reactions mayoccur to form additional cement products, such as calcium aluminatehydrates. Additionally, alumina may be present in the silica source. Asused herein, alumina is understood to have the plain and ordinarymeaning of aluminum oxide (Al₂O₃). Calcium hydroxide necessary for thereaction may be provide from other cement components, such as Portlandcement, or may be separately added to the cement composition. Examplesof suitable silica sources may include fly ash, slag, silica fume,crystalline silica, silica flour, cement kiln dust (“CKD”), volcanicrock, perlite, metakaolin, diatomaceous earth, zeolite, shale, andagricultural waste ash (e.g., rice husk ash, sugar cane ash, and bagasseash), among other. Some specific examples of the silica source will bediscussed in more detail below. Where present, the silica sourcegenerally may be included in the cement compositions in an amountsufficient to provide the desired compressive strength, density, and/orcost. The silica source may be present in the cement compositions in anysuitable amount, including, but not limited to an amount in the range ofabout 0% to about 99% bwoc. In some examples the silica source may bepresent in an amount ranging between any of and/or including any ofabout 1%, about 5%, about 10%, about 20%, about 40%, about 60%, about80%, or about 90% bwoc. Those of ordinary skill in the art, with thebenefit of this disclosure, should be able to select an appropriateamount of silica source for a particular application.

Amorphous silica may also be present. Amorphous silica may preventstrength retrogression. In general, amorphous silica may not requiretemperatures above 235° F. to participate in cement hydrations.Amorphous silica may protect against strength retrogression and maximizedesign efficiency by eliminating the need for multiple designs atdifferent temperatures. Amorphous silica may also replace crystallinesilica in some applications.

An example of a suitable silica source may comprise fly ash. A varietyof fly ash may be suitable, including fly ash classified as Class C andClass F fly ash according to American Petroleum Institute, APISpecification for Materials and Testing for Well Cements, APISpecification 10, Fifth Ed., Jul. 1, 1990. Class C fly ash comprisesboth silica and lime, so it may set to form a hardened mass upon mixingwith water. Class F fly ash generally does not contain a sufficientamount of lime to induce a cementitious reaction, therefore, anadditional source of calcium ions is necessary for a set-delayed cementcomposition comprising Class F fly ash. In some embodiments, lime may bemixed with Class F fly ash in an amount in the range of about 0.1% toabout 100% by weight of the fly ash. In some instances, the lime may behydrated lime. Suitable examples of fly ash include, but are not limitedto, POZMIX® A cement additive, commercially available from HalliburtonEnergy Services, Inc., Houston, Tex.

Another example of a suitable silica source may comprise slag. Slag isgenerally a by-product in the production of various metals from theircorresponding ores. By way of example, the production of cast iron canproduce slag as a granulated, blast furnace by-product with the slaggenerally comprising the oxidized impurities found in iron ore. Slaggenerally does not contain sufficient basic material, so slag cement maybe used that further may comprise a base to produce a settablecomposition that may react with water to set to form a hardened mass.Examples of suitable sources of bases include, but are not limited to,sodium hydroxide, sodium bicarbonate, sodium carbonate, lime, andcombinations thereof.

Another example of a suitable silica source may comprise CKD. Cement kindust or “CKD”, as that term is used herein, refers to a partiallycalcined kiln feed which is removed from the gas stream and collected,for example, in a dust collector during the manufacture of cement.Usually, large quantities of CKD are collected in the production ofcement that are commonly disposed of as waste. Disposal of the CKD aswaste can add undesirable costs to the manufacture of the cement, aswell as the environmental concerns associated with its disposal. CKD isanother component that may be included in examples of the cementcompositions.

Another example of a suitable silica source may comprise volcanic rock.Certain volcanic rocks may exhibit cementitious properties, in that itmay set and harden in the presence of hydrated lime and water. Thevolcanic rock may also be ground, for example. Generally, the volcanicrock may have any particle size distribution as desired for a particularapplication. In certain embodiments, the volcanic rock may have a meanparticle size in a range of from about 1 micron to about 200 microns.The mean particle size corresponds to d50 values as measured by particlesize analyzers such as those manufactured by Malvern Instruments,Worcestershire, United Kingdom. One of ordinary skill in the art, withthe benefit of this disclosure, should be able to select a particle sizefor the volcanic rock suitable for a chosen application.

Another example of a suitable silica source may comprise metakaolin.Generally, metakaolin is a white pozzolan that may be prepared byheating kaolin clay, for example, to temperatures in the range of about600° to about 800° C.

Another example of a suitable silica source may comprise shale. Amongother things, shale included in the cement compositions may react withexcess lime to form a suitable cementing material, for example, calciumsilicate hydrate. A variety of shales are suitable, including thosecomprising silicon, aluminum, calcium, and/or magnesium. An example of asuitable shale comprises vitrified shale. Generally, the shale may haveany particle size distribution as desired for a particular application.In certain embodiments, the shale may have a particle size distributionin the range of about 37 micrometers to about 4,750 micrometers.

Another example of a suitable silica source may comprise zeolite.Zeolites generally are porous alumino-silicate minerals that may beeither a natural or synthetic material. Synthetic zeolites are based onthe same type of structural cell as natural zeolites, and may comprisealuminosilicate hydrates. As used herein, the term “zeolite” refers toall natural and synthetic forms of zeolite. Examples of zeolites mayinclude, without limitation, mordenite, zsm-5, zeolite x, zeolite y,zeolite a, etc. Furthermore, examples comprising zeolite may comprisezeolite in combination with a cation such as Na⁺, K⁺, Ca²⁺, Mg²⁺, etc.Zeolites comprising cations such as sodium may also provide additionalcation sources to the cement composition as the zeolites dissolve.

The cement compositions may further comprise hydrated lime. As usedherein, the term “hydrated lime” will be understood to mean calciumhydroxide. In some examples, the hydrated lime may be provided asquicklime (calcium oxide) which hydrates when mixed with water to formthe hydrated lime. The hydrated lime may be included in examples of thecement compositions, for example, to form a hydraulic composition withthe silica source. For example, the hydrated lime may be included in asilica source-to-hydrated-lime weight ratio of about 10:1 to about 1:1or a ratio of about 3:1 to about 5:1. Where present, the hydrated limemay be included in the cement compositions in an amount in the range offrom about 10% to about 100% by weight of the silica source, forexample. In some examples, the hydrated lime may be present in an amountranging between any of and/or including any of about 10%, about 20%,about 40%, about 60%, about 80%, or about 100% by weight of the silicasource. One of ordinary skill in the art, with the benefit of thisdisclosure, should recognize the appropriate amount of hydrated lime toinclude for a chosen application.

In some examples, the cement compositions may comprise a calcium sourceother than hydrated lime. In general, calcium and a high pH, for examplea pH of 7.0 or greater, may be needed for certain cementitious reactionsto occur. A potential advantage of hydrated lime may be that calciumions and hydroxide ions are supplied in the same molecule. In anotherexample, the calcium source may be Ca(NO₃)₂ or CaCl₂ with the hydroxidebeing supplied form NaOH or KOH, for example. One of ordinary skillwould understand the alternate calcium source and hydroxide source maybe included in a cement composition in the same way as hydrated lime.For example, the calcium source and hydroxide source may be included ina silica source-to-hydrated-lime weight ratio of about 10:1 to about 1:1or a ratio of about 3:1 to about 5:1. Where present, the alternatecalcium source and hydroxide source may be included in the cementcompositions in an amount in the range of from about 10% to about 100%by weight of the silica source, for example. In some examples, thealternate calcium source and hydroxide source may be present in anamount ranging between any of and/or including any of about 10%, about20%, about 40%, about 60%, about 80%, or about 100% by weight of thesilica source. One of ordinary skill in the art, with the benefit ofthis disclosure, should recognize the appropriate amount of alternatecalcium source and hydroxide source to include for a chosen application.

A target silica lime ratio may be defined and a cement additivecomprising two or more cement components may be identified that meetsthe silica lime ratio. In some examples, the target silica lime ratiomay range from about 80/20 silica to free lime by weight to about 60/40silica to free lime by weight, for example, be about 80/20 silica tofree lime by weight, about 70/30 silica to free lime by weight, or about60/40 silica to free lime by weight. The silica lime ratio may bedetermined by measuring the available silica and lime for a given cementcomponent.

Other additives suitable for use in cementing operations also may beincluded in embodiments of the cement compositions. Examples of suchadditives include, but are not limited to: weighting agents, retarders,accelerators, activators, gas control additives, lightweight additives,gas-generating additives, mechanical-property-enhancing additives,lost-circulation materials, filtration-control additives,fluid-loss-control additives, defoaming agents, foaming agents,dispersants, thixotropic additives, suspending agents, and combinationsthereof. One of ordinary skill in the art, with the benefit of thisdisclosure, should be able to select an appropriate additive for aparticular application.

As mentioned previously, in order to determine if two or more of theaforementioned cement components are compatible, several lab tests maybe run. Additionally, any potential synergistic effects of the cementcomponent may not be known unless several laboratory tests areperformed. Typically, a known cement composition may be first formulatedand tested for properties such as, for example, the 24 hour compressivestrength, fluid loss, and thickening time. Then, varying amounts ofadditives may be added to a fresh batch of cement compositions and thetests are re-run. The results are gathered form each test and compared.A new set of tests may then be run with new concentrations of additives,for example, to adjust properties of the cement composition. The processof testing various additives in varying concentrations may go on forseveral trials until an acceptable cement composition or compositions isformulated. An acceptable cement composition may be one that meetscertain design requirements, such as compressive strength, fluid loss,and thickening time. The cement composition design process may be donein a heuristic manner leading to a cement composition that may have therequired engineering properties but may not be optimized for cost.Additionally, silica sources such as, for example, CKD, have beenpreviously used as either pure fillers or in some examples, reactivecomponents, in Portland based cement compositions. CKD will contribute aportion of silica which requires a portion of lime to react. In methodsof cement composition formulation described above, the heuristic processdoes not take into account the silica to lime ratio of a composition.

The method described herein may reduce or eliminate the heuristic searchfor by a process that identifies a cement additive through a process ofmeasuring and categorizing a variety of cement components referred to asreactivity mapping. Reactivity mapping may generate a correlationbetween properties of inorganic particles. Reactivity mapping maycomprise several steps. One step may comprise measuring the physical andchemical properties of different materials through standardized tests.Another step may comprise categorizing the materials through analysis ofdata collected and the predicted effect on cement slurry properties. Yetanother step may comprise utilizing the data to estimate materialreactivity, improve cement performance, predicting blend mechanicalproperties mathematically based on analytical results, and/or predictslurry density dependence of compressive strength.

Measuring physical and chemical properties of each selected cementcomponent may comprise many laboratory techniques and proceduresincluding, but not limited to, microscopy, spectroscopy, x-raydiffraction, x-ray fluorescence, particle size analysis, waterrequirement analysis, scanning electron microscopy, energy-dispersiveX-ray spectroscopy, surface area, specific gravity analysis,thermogravimetric analysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio. One or more of the proceeding tests may be consider API tests, asset forth in the API recommended practice for testing well cements(published as ANSI/API recommended practice 10B-2). Additional API testsnot specifically listed above may also be used for the measurements. Thephysical and chemical properties may be measured for a group of cementcomponents. Two or more of the cement components measured may bedifferent types of cement components (e.g., volcanic rock, CKD, fly ash,etc.). Two or more of the cement components may be the same type butfrom different sources (e.g., volcanic rock from source 1, volcanic rockfrom source 2, etc.).

X-ray powder diffraction is one analysis technique that may be used formeasuring the physical and chemical properties of the cement components.X-ray powder diffraction is a technique of exposing a sample to x-rays,neutrons, or electrons and measuring the amount ofinter-atomic-diffraction. The sample acts a diffraction grating therebyproducing a differing signal at different angles. The typical propertiesthat may be measured are the phase identification for the identificationand characterization of a crystalline solid. Other properties may becrystallinity, lattice parameters, expansion tensors, bulk modulus, andphase transitions.

X-ray fluorescence is another analysis technique that may be used formeasuring the physical and chemical properties of the cement components.X-ray fluorescence may use short wave x-rays to ionize atoms in a samplethereby causing them to fluoresce at certain characteristic wavelengths.The characteristic radiation released by a sample may allow accurateidentification of the component atoms in the sample as well as theirrelative amounts.

Particle size analysis is another analysis technique that may be usedfor measuring the physical and chemical properties of the cementcomponents. Particle size analysis may be accomplished through analysisby various laboratory techniques including but not limited to laserdiffraction, dynamic light scattering, static image analysis, anddynamic image analysis. Particle size analysis may also provideinformation about the morphology of a particular sample. Morphology mayinclude parameters such as sphericity and roundness as well as thegeneral shape of a particle such as disk, spheroid, blade, or roller.With a knowledge of the morphology and particle size, the averagesurface area and volume may be estimated. Surface area and volume may beimportant in determining the water requirement as well as reactivity. Ingeneral, a relatively smaller particle size may react more quickly thana relatively larger particle size. Also the relatively smaller particlesize may have a greater water requirement to completely hydrate than arelatively larger particle size.

Energy dispersive x-ray spectroscopy is another analysis technique thatmay be used for measuring the physical and chemical properties of thewaste materials. Energy dispersive x-ray spectroscopy is an analyticaltechnique used to analyze the elements present in a sample and determinethe chemical characterization of a sample. Other techniques may includeFourier transform infrared spectroscopy, ultraviolet-visiblespectroscopy, mass spectroscopy, secondary ion mass spectrometry,electron energy mass spectrometry, dispersive x-ray spectroscopy, augerelectron spectroscopy, inductively coupled plasma mass spectrometry(ICP-MS), thermal ionization mass spectroscopy, glow discharge massspectroscopy, and x-ray photoelectron spectroscopy.

The cement components may be analyzed to determine their waterrequirement. Water requirement is typically defined as the amount ofmixing water that is required to be added to a powdered, solid materialto form a slurry of a specified consistency. Water requirement for aparticular cement component may be determined by a process that includesa) preparing a Waring blender with a specified amount of water, b)agitating the water at a specified blender rpm, c) adding the powderedsolid that is being investigated to the water until a specifiedconsistency is obtained, and d) calculating the water requirement basedon the ratio of water to solids required to reach the desiredconsistency.

The cement components may be analyzed to determine their specificsurface area. Specific surface area generally refers to the totalsurface area and may be reported as the total surface area per unitmass. Values obtained for specific area are dependent on the analysistechnique. Any suitable analysis technique may be used, includingwithout limitation adsorption based methods such asBrunauer-Emmett-Teller (BET) analysis, methylene blue staining, ethyleneglycol monoethyl ether adsorption, and a protein-retention method, amongother.

Thermogravimetric analysis is another analysis technique that may beused for measuring the physical and chemical properties of the cementcomponents. Thermogravimetric analysis is a method of thermal analysiswherein changes in physical and chemical properties of a sample may bemeasured. In general the properties may be measured as a function ofincreasing temperature, such as with a constant heating rate, or as afunction of time with a constant temperature or a constant mass change.Properties determined by thermogravimetric analysis may includefirst-order phase transitions and second-order phase transitions such asvaporization, sublimation, adsorption, desorption, absorption,chemisorption, desolvation, dehydration, decomposition, oxidation andreduction reactions, ferromagnetic transition, superconductingtransition, and others.

In addition to determining physical and chemical properties of thecement components themselves, laboratory tests may also be run todetermine behavior of the cement components in a cement composition. Forexample, the cement components may be analyzed in a cement compositionto determine their compressive strength development and mechanicalproperties. For example, a preselected amount of the cement componentmay be combined with water and lime (if needed for setting). Themechanical properties of the cement composition may then be determinedincluding, compressive strength, tensile strength, and Young's modulus.Any of a variety of different conditions may be used for the testing solong as the conditions are consistent for the different cementcomponents.

Compressive strength is generally the capacity of a material orstructure to withstand axially directed pushing forces. The compressivestrength of the cement component may be measured at a specified timeafter the cement component has been mixed with water and the resultantcement composition is maintained under specified temperature andpressure conditions. For example, compressive strength can be measuredat a time in the range of about 24 to about 48 hours (or longer) afterthe fluid is mixed and the fluid is maintained at a temperature of from100° F. to about 200° F. and atmospheric pressure. Compressive strengthcan be measured by either a destructive method or non-destructivemethod. The destructive method physically tests the strength oftreatment fluid samples at various points in time by crushing thesamples in a compression-testing machine. The compressive strength iscalculated from the failure load divided by the cross-sectional arearesisting the load and is reported in units of pound-force per squareinch (psi). Non-destructive methods typically may employ an UltrasonicCement Analyzer (“UCA”), available from Fann® Instrument Company,Houston, Tex. Compressive strengths may be determined in accordance withAPI RP 10B-2, Recommended Practice for Testing Well Cements, FirstEdition, July 2005.

Tensile strength is generally the capacity of a material to withstandloads tending to elongate, as opposed to compressive strength. Thetensile strength of the cement component may be measured at a specifiedtime after the cement component has been mixed with water and theresultant cement composition is maintained under specified temperatureand pressure conditions. For example, tensile strength can be measuredat a time in the range of about 24 to about 48 hours (or longer) afterthe fluid is mixed and the fluid is maintained at a temperature of from100° F. to about 200° F. and atmospheric pressure. Tensile strength maybe measured using any suitable method, including without limitation inaccordance with the procedure described in ASTM C307. That is, specimensmay be prepared in briquette molds having the appearance of dog biscuitswith a one square inch cross-sectional area at the middle. Tension maythen be applied at the enlarged ends of the specimens until thespecimens break at the center area. The tension in pounds per squareinch at which the specimen breaks is the tensile strength of thematerial tested.

Young's modulus also referred to as the modulus of elasticity is ameasure of the relationship of an applied stress to the resultantstrain. In general, a highly deformable (plastic) material will exhibita lower modulus when the confined stress is increased. Thus, the Young'smodulus is an elastic constant that demonstrates the ability of thetested material to withstand applied loads. A number of differentlaboratory techniques may be used to measure the Young's modulus of atreatment fluid comprising a cementitious component after the treatmentfluid has been allowed to set for a period of time at specifiedtemperature and pressure conditions.

Although only some select laboratory techniques may have been mentioned,it should be understood that there may be many analytical techniquesthat may be appropriate or not appropriate for a certain sample. One ofordinary skill in the art with the benefit of this disclosure should beable to select an appropriate analytical technique to determine acertain property of interest.

Once analytical techniques have been performed on the cement components,the data may be categorized and correlated. Some categories may include,but are not limited to, specific surface area, morphology, specificgravity, water requirement, etc. In some examples, the components may becategorized by relative amounts, including amount of at least onefollowing: silica, alumina, iron, calcium, sodium, potassium, magnesium,sulfur, oxides thereof, and combinations thereof. For example, thecomponents may be categorized based on an oxide analysis that includeswithout limitation, silica content, calcium oxide content, and aluminacontent among other oxides that may be present in the cement component.In addition, correlations between the cement components may be generatedbased on the data or categorization of the data. Additionally,correlations may be defined or generated between properties of thecement components based on the data. For example, the various categoriesof properties may be plotted against one another. In some examples,water requirement versus specific surface area may be plotted.Accordingly, the water requirement of the cement component may becorrelated to the specific surface area so that the specific surfacearea is a function of water requirement. Specific surface area may beused to predict reactivity of a cement component (or components).However, specific surface area may not always be available for eachmaterial as specific surface area analysis typically requires aspecialized instrument. Accordingly, if the water requirement may beobtained for the cement component, the correlation between waterrequirement and specific surface area may be used to obtain an estimatefor specific surface area, which may then be used to predict reactivity.In addition to correlations between specific surface area andreactivity, correlations may also be made between specific surface areaand other mechanical properties such as tensile strength and Young'smodulus.

Some cement components that are alkali soluble may comprise reclaimed ornatural materials. Specifically silica containing cement components maycomprise materials such as mined materials, for example volcanic rock,perlite, waste materials, such as fly ash and CKD, and agriculturalashes as previously described. In some examples the cement componentthat is alkali soluble may have synergistic effects with a Portlandcement while others may be incompatible. In some examples a cementcomponent that is alkali soluble may cause gelation, high heatgeneration, water retention, among other effects. These and othereffects may be realized during laboratory testing of the cementcomponent in a cement composition comprising Portland cement. Laboratoryequipment may be configured to detect the effects of the cementcomponent on the composition. In some examples, equipment such acalorimeter may measure and quantify the amount of heat generation perunit mass of the cement component. Viscometers may measure the increasein gelation caused by the cement component. Each of the physical effectscaused by the addition of the cement component may be measured atseveral concentrations and then categorized, e.g., plotted or mapped.Once a component is mapped, the effect of adding the component to acement composition may be predicted by referencing the categorization.

As mentioned previously, some cement components that are alkali solublemay induce gelling when included in a cement composition. Although ahigher gelling rate may be undesirable in some examples, in otherexamples, a higher gelling rate may be advantageous or necessary to meetthe engineering design criteria. Usually one of ordinary skill in theart would select a suitable gelling agent or viscosifier for use in thecement composition. With the benefit of mapping, one of ordinary skillshould be able to select a cement component that is alkali soluble thatmay serve a dual purpose. For example, a cement component may increasethe compressive strength of a cement composition but also increase thegelling during mixing. If the engineering design criteria requires ahigher gelling during mixing, it may be advantageous to include thecement component that increases the compressive strength while alsoincreasing gelling. The inclusion of a cement component that exhibitsmultiple effects may reduce the amount of additional additives, such asgelling agents or viscosifiers, needed, which may be high cost. Sincethe component's gelling effect may have been documented in a map, theamount of component to include in a cement composition may be readilydetermined.

Another potentially advantageous physical effect that may be mapped isdispersing ability. Some cement components may comprise relativelyspherical particles. The relatively spherical particles may exert a“roller bearing” effect in a cement composition with water. The effectmay cause the other components in the cement composition to become moremobile thereby dispersing the components in the cement composition. Ifparticles that are roughly 1/7^(th) or smaller than the primarycomponent in a slurry, then the apparent viscosity may decrease. Anotherpotentially advantageous physical property that may be mapped is surfacearea. Surface area may relate to density wherein a relatively highersurface area particle may lower the density of a cement composition.Particles which lower the density may be used as a low density additive.Another potentially advantageous effect that may be mapped is particlesize. Components with relatively smaller particle sizes may have theability to form a filter cake against a formation thereby blockingcement from escaping into a formation. Cement components with a smallparticle size may be used as a fluid loss control agent. With thebenefit of the present disclosure, one of ordinary skill should be ableto select a cement component and map its properties. One of ordinaryskill should also be able to select a secondary property of interest ofthe cement component and with the benefit of the map, create a slurrywith the desired properties.

Another potential benefit of replacing traditional cement additives withsilica based cement components is a reduction in cost. A silica basedcement component may partially or fully replace a relatively moreexpensive cement additive as discussed above. The cost of the cementcomposition may be improved by balancing the required engineeringparameters such as compressive strength, mix ability, free watercontent, and others in order to maximize the amount of relatively lowercost silica based cement components. Any remaining deviation from theengineering requirement may be “made up” with the relatively moreexpensive cement additive. In this way, the cement composition may bereduced to a minimum cost per pound since the engineering requirementsare met with a blend of primarily lower cost components.

Once the data is collected by the chosen laboratory techniques,categorized, and mapped, several operations may be performed on the datain order to yield predictions about a cement composition that comprisesmapped cement components. Set properties, for example, may be estimated.A method of estimating the material reactivity based on the reactiveindex will be described below. Material reactivity may be based on manyparameters such as specific surface area and specific gravity, amongothers. Another use for the mapped data may be to increase cement slurryperformance based on parameters such as particle shape, particle size,and particle reactivity. The data may also be used to predict andcapture slurry density dependence of compressive strength and use theinsight gathered to design improved cement formulations. The data mayalso be used to predict a slurry composition to achieve an improvedcement formulation. The criteria for just right may be compressivestrength, cost, rheology, mechanical properties, fluid loss controlproperties, thickening times, and others.

Reactivity mapping may be used to estimate various mechanical propertiesof a cement component, including compressive strength, tensile strength,and Young's modulus. As previously described, correlations may be madebetween specific surface area and certain mechanical properties, such asreactivity, tensile strength, and Young's modulus. Using thesecorrelations the mechanical properties for a cement component orcombination of cement components may be predicted.

One technique that may be used to correlate reactivity and specificsurface area is the reactive index. Without being limited by theory, thereactive index of a cement component may be referred to as a measure ofthe cement component's reactivity as adjusted for differences in surfacearea. It is important to note that the term “cement component” refers toany material that is cementitious when mixed with water and/or lime anda suspending agent, when necessary, such that the slurry is stable. A“cementitious reactive index” CRI_(i) can be defined as, but not limitedto, Equation [1] as follows:CRI _(i) =f _(CRI)(CS _(i),ρ_(i) ,SSA _(PSDi),)  [1]

-   -   Where:    -   CS_(i)=Unconfined UCS (ultimate compressive strength) obtained        from samples cured at specific reference temperature, pressure        and age.    -   ρ_(i)=Density of slurry that was prepared and cured for        measuring UCS    -   SSA_(PSDi)=Specific surface area obtained by typical particle        size analysis methods.        A “physicochemical index” (PCI) of the cementitious component        may be defined as, but not limited to Equation [2]:        PCI _(i) =f _(PCI)(SA _(i) ,SG _(i) ,D ₅₀ ,C _(Si) ,C _(Ca) ,C        _(Al) ,C _(Na) ,C _(Fe) ,C _(other species))  [2]    -   Where:    -   SA_(i)=Surface area of the cementitious component i,    -   SG_(i)=specific gravity of the cementitious component i,    -   D₅₀=mass average or volume average diameter of the particle size        distribution of cementitious component i,    -   C_(Si)=Mass concentration of silica oxide of component i,    -   C_(Ca)=Mass concentration of calcium oxide of component i,    -   C_(Al)=Mass concentration of Aluminum oxide of component i,    -   C_(Na)=Mass concentration of sodium oxide of component i,    -   C_(Fe)=Mass concentration of iron oxide of component i,

It should be noted that the mass concentrations referenced above andhere to for, may be measured, but is not limited to X-ray fluorescencespectroscopy measuring technique and a reference to “component i” isequivalent to “cementitious component i”. The functions in Equations [1]and [2] that define CRI_(i) and PCI_(i), when properly defined, thefollowing universal relationship may hold for a wide range ofcementitious materials such as, but not limited to, Portland cements;fly ash; other pozzolanic materials; other ashes; etc.CRI _(i) =f _(CRI-PCI)(PCI _(i))  [3]FIG. 1 is a graph of Equation [1] versus Equation [2] for real data,illustrating the accuracy of Equations [1], [2] and [3] when applied tofive different types of cementitious material sources and three samplesof similar materials but from different sources. The simulated data wasfound to have a relationship of y=36.252x^(0.2256,) wherein R²=0.9406.

In some examples, the form of Equation [3] may be a power law, such asin Equation 4.CRI _(i) =A{PCI _(i)}^(B)  [4]A and B are coefficients that may be unique the various species andsources of cementitious materials selected. Once the generalizedfunction defined in Equation [4] is defined for a given population orgroup of cementitious components, a linear or nonlinear summationrelationship further defined below, may be used in conjunction withEquation [5] to predict the UCS of various combinations of cementitiousmaterials for specified slurry densities, temperatures, pressures andcuring age.CRI _(c) =A{PCI _(c)}^(B)  [5]

-   -   Where,    -   CRI_(c)is defined as the CRI for the unique combination of n        cementitious components as the composite, and similarly    -   PCI_(c) is defined as the Physicochemical Index for the        composite.        A given composite with mass of m_(c) is defined as:        m _(c) =f _(i) +f _(i+1) +f _(i+2) +f _(n)  [6]        Where: f_(i) is defined as the mass fraction of the cementitious        component i, and n is the total number of independent        cementitious components. Once the function is defined in        Equation [5], then the composite value of the physicochemical        reactive index may be computed using Equation [7] as follows:        PCI _(c) =f ₁ PCI ₁ +f ₂ PCI ₂ +f ₃ PCI ₃ + . . . +f _(n) PCI        _(n)  [7]

Where: PCI_(c) is defined as the overall chemical reactive index for ablend of n number of uniquely independent cementitious components, f_(i)is defined as the mass fraction of the cementitious component i, and nis the total number of independent cementitious components. Once PCI_(c)has been determined for specific assumed blend of selected cementitiouscomponents, then the linear or non-linear summations (Equations [8] and[9]) are determined for the following terms:ρ_(c) =f ₁ρ₁ +f ₂ρ₂ +f ₃ρ₃ + . . . +f _(n)ρ_(n)  [8]and,SSA _(PSDc) =f ₁ SSA _(PSD1) +f ₂ SSA _(PSD2) +f ₃ SSA _(PSD3) + . . .+f _(n) SSA _(PSDn)  [9]PCI_(c) is used to compute the value of CRI_(c) using either Equation[5] or the more generalized form of Equation [3] for the compositeterms. Once CRI_(c) is determined for the given composite blend, thenthe composite values of ρ_(c) and SSA_(PSDc) may be used along withEquation [10] to predict the actual compressive strength of thecomposite blend, CS_(c).CRI _(c) =f _(CRI)(CS _(c),ρ_(c) ,SSA _(PSDc),)  [10]Experimental data was collected for specific composite blends issummarized in the table below:

TABLE 1 Mass Fractions of Cementitious Components Cementitious CompositeComposite Composite Component Blend 1 Blend 2 Blend 3 A 0.36 0.53 B 0.32C 0.32 0.31 D 0.33 E 0.32 F 0.35 G 0.16 Totals 1.00 1.00 1.00It is important to note that each of the cementitious components abovewere either distinctly different species (type) of cementitiouscomposition and/or from a different source.

FIG. 2 is another plot of Equation [1] versus Equation [2] for real datashowing the accuracy of Equations [1], [2], and [3]. Equations [1]through [10] may also be used for predicting other mechanicalproperties, including but not limited to, Young's Modulus of Elasticityand Tensile Strength. Additionally, it should be noted that even thougha “linear summation” technique is presented in the previous development,that this invention also includes other methods such as the non-linearsummation method presented in Equation [11].PCI _(c)=(1+f ₁)^(a1) PCI ₁+(1+f ₂)^(a2) PCI ₂+(1+f ₃)_(a3) PCI ₃+ . . .+(1+f _(n))^(an) PCI _(n)   [11]Where: ai are exponents that are determined for a unique set ofcementitious components.

Further examples using the chemical reactive index, water requirementand other analytical parameters will now be discussed. A statisticaltable may be generated that plots chemical reactive index against waterrequirement. An example is shown in Table 2.

TABLE 2 Chemical Reactive Index Vs. Water Requirement Water RequirementHigh X1 X4, X5 X8 Medium X2 X6 X9, X10 Low X3 X7 X11 . . . Xn Low MediumHigh Chemical Reactive IndexOther analytical parameters such as particle size versus chemicalreactive index, heat generation versus chemical reactive index, andothers may also be used. By ranking the chemical reactive index againstan analytical parameter, a blend of components may be selected that hasa minimized cost and an improved chemical reactive index while stillhaving a mixable composition. In some examples, a selected cementcomposition may have too much free water to set properly. In suchexamples, a component having a high water requirement may be selected toreplace a component in the cement composition or supplement the cementcomposition. The selected component having the high water requirementmay be selected based on the chemical reactive index to ensure that theoverall blend has sufficient reactivity. A cement composition comprisingthe selected cement component may exhibit less free water due to thehigh water requirement of the component and may also exhibit the samereactivity from selecting the appropriate chemical reactive index. Thereactivity of a cement composition may be tuned based on the selectionof cement component having the desired reactivity. A component having ahigh reactivity may exhibit a faster set time that one with a lowreactivity.

The reactivity of a cement composition may be affected by wellboretemperature. If a wellbore has a relatively low temperature, about <150°F. or less, a component having a relatively higher reactivity may berequired to ensure that the cement composition develops adequatestrength. In previous cement compositions, a chemical accelerator mayhave been used to enhance the reaction speed in a relatively lowertemperature well. A cement composition comprising a relatively higherchemical reactive index component may not require an accelerator due tothe high reactivity of the component. Cement compositions comprising ahigh reactivity component may not require an accelerator and thereforemay have a lower overall cost. If a wellbore has a relatively hightemperature, about >150° F. or greater, the cement component may beselected to have a relatively lower reactivity. Selecting a lowerreactivity may be advantageous when the high temperature of a wellboremay cause the cement composition to set too quickly. In previous cementcompositions, a cement set retarder may have been used to reduce thereaction speed in a relatively higher temperature well. By selecting arelatively lower reactivity component, the cement set reaction maypotentially be slowed without the use of a retarder. The Selecting anappropriate cement component based on reactivity may reduce the cost ofthe cement composition by eliminating or reducing the need foraccelerators and retarders. Furthermore, a combination of cementcomponents may be blended to control the reactivity, for example byadding low, medium, and high reactivity cement components, a cementcomposition may be created that has a controlled reactivity along thespectrum of wellbore temperatures. One of ordinary skill in the art,with the benefit of this disclosure, should recognize the appropriateamount and type of cement component to include for a chosen application.

Another application of the previously mention statistical correlationmay be in classifying cement components by cost among other factors. Ingeneral, the reactivity of a cement composition may be maximized toensure that the cement composition will attain enough compressivestrength to meet the design requirement of a particular well. If aspecific cement composition far exceeds the engineering requirements,then an alternate cement composition comprising potentially lessexpensive components may be formulated. The following equationsillustrate an improvement scheme for a cement composition.

$\begin{matrix}{{CRI},{{composite} = {\sum\left( {{CRI}_{i}*\%{Concentration}} \right)}}} & \lbrack 12\rbrack\end{matrix}$ $\begin{matrix}{{{Cost}{Index}},{{composite} = {\sum\left( {{Cost}_{i}*\%{Concentration}} \right)}}} & \lbrack 13\rbrack\end{matrix}$ $\begin{matrix}{\left. {{Optimized}{Blend}}\rightarrow{\max{CRI}} \right.,{{composite}\Lambda\min{Cost}{Index}},{composite}} & \lbrack 14\rbrack\end{matrix}$ $\begin{matrix}{{{{Optimization}{Ratio}} = {\max\left\lbrack \frac{{CRi},{composite}}{{{Cost}{Index}},{composite}} \right\rbrack}}{{{{Constraints}:{Cost}{Index}} < {\$ C}},{{{where}C} \geq 0}}{{{CS} = \left. {f\left( {{CRI},{{analytical}{properies}}} \right)}\rightarrow{CS} \right.},{\min < {CS}},{{composite} < {CS}},\max}} & \lbrack 15\rbrack\end{matrix}$

Using all the techniques previously discussed, a cement compositionhaving a minimized cost and a maximized reactivity may be calculated. Afirst step may be to identify the engineering requirements of aparticular well. Another step may be to define the inventory availableat a particular field camp or well site. As previously mentioned, aparticular region may have access to only a certain amount or kind ofcement components. Some of the factors that may be considered inaddition to those previously mentioned are the cost of goods sold, bulkdensity, and specific gravity for the available and potential inventory.The available cement components may be tested in a laboratory andclassified using the methods previously discussed. Analytical study maycomprise the various analytical techniques previously mentioned alongwith the physicochemical reactivity measurements for compressivestrength, young's modulus, water requirement, and others. Next thecorrelations between the mechanical performance measures and analyticalproperties may be calculated. The chemical reactive index may also becalculated. A statistical table of the chemical reactive index and thewater requirement may be calculated along with the chemical reactiveindex versus other selected analytical parameters.

An initial virtual design may be selected and tested to see if it meetsthe functional requirements defined by the engineering parameters. Theinitial virtual design may be based on a previous design, chosen fromfield experience, or selected by a computer. The virtual design may bebased on, among other factors, the chemical reactivity of the cementcomponents. If the virtual design meets all of the engineeringparameters, a cost index for the composition may be calculated. Thecomponents of the cement composition may be adjusted iteratively until acement composition having the maximum reactive index and minimized costis achieved. In some examples, a fluid loss control additive, thickeningadditive, or other cement additives may be necessary to meet thefunctional requirements. As was previously described, the amount ofcement additives that may need to be added to a cement composition maybe minimized by selecting cement components that have inherentproperties such as high reactive index, low water requirement, fluidloss control properties, and dispersive properties, among others.

As will be appreciated by those of ordinary skill in the art, the cementcompositions disclosed herein may be used in a variety of subterraneanapplications, including primary and remedial cementing. The cementcompositions may be introduced into a subterranean formation and allowedto set. As used herein, introducing the cement composition into asubterranean formation includes introduction into any portion of thesubterranean formation, into near wellbore region surrounding thewellbore, or into both. In primary cementing applications, for example,the cement compositions may be introduced into the annular space betweena conduit located in a wellbore and the walls of the wellbore (and/or alarger conduit in the wellbore), wherein the wellbore penetrates thesubterranean formation. The cement composition may be allowed to set inthe annular space to form an annular sheath of hardened cement. Thecement composition may form a barrier that prevents the migration offluids in the wellbore. The cement composition may also, for example,support the conduit in the wellbore. In remedial cementing applications,the cement compositions may be used, for example, in squeeze cementingoperations or in the placement of cement plugs. By way of example, thecement compositions may be placed in a wellbore to plug an opening(e.g., a void or crack) in the formation, in a gravel pack, in theconduit, in the cement sheath, and/or between the cement sheath and theconduit (e.g., a microannulus).

While the present description refers to cement compositions and cementcomponents, it should be understood that the techniques disclosed hereinmay be used with any suitable wellbore treatment composition andcorresponding solid particulates of which cement compositions and cementcomponents are one example. Additional examples of slurry compositionsmay include spacer fluids, drilling fluids, cleanup pills, lostcirculation pills, and fracturing fluids, among others. In addition,while the preceding descriptions describes silica sources, it should beunderstood that present techniques may be used for mapping othersuitable inorganic particulates.

Statement 1: A method comprising: analyzing each of a group of inorganicparticles to generate data about physical and/or chemical properties ofthe inorganic particles; generating correlations between the inorganicparticles based on the data.

Statement 2: The method of statement 1 further comprising generating astatistical table comprising two or more different parameters of theinorganic particles.

Statement 3: The method of statement 1 further comprising preparing acement composition comprising the inorganic particles and allowing thecement composition to set in a wellbore.

Statement 4: The method of statement 1 wherein at least one of theinorganic particles comprises at least one of silica, alumina, iron,iron oxide, calcium, calcium oxide, sodium, potassium, magnesium,sulfur, and combinations thereof.

Statement 5: The method of statement 1 wherein the analyzing theinorganic particles comprises analysis by one or more techniquesselected from the group consisting of microscopy, spectroscopy, x-raydiffraction, x-ray fluorescence, particle size analysis, waterrequirement analysis, scanning electron microscopy, energy-dispersiveX-ray spectroscopy, surface area, specific gravity analysis,thermogravimetric analysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio, API testing, and combinations thereof.

Statement 6: The method of statement 1 wherein the data comprises anamount of at least component selected from the group consisting ofsilica, alumina, iron, calcium, sodium, potassium, magnesium, sulfur,oxides thereof, and combinations thereof.

Statement 7: The method of statement 1 wherein the data comprisesaverage particle size, particle size distribution, and morphology foreach of the inorganic particles.

Statement 8: The method of particles 1 wherein the data comprisesspecific surface area for each of the inorganic particulates.

Statement 9: The method of statement 1 wherein the correlationscomprises at least a correlation of specific surface area for each ofthe cement components to water requirement for each of the inorganicparticles.

Statement 10: The method of statement 1 further comprising identifying acement additive comprising two or more of the inorganic particles, andpredicting one or more mechanical properties of a cement compositioncomprising the cement additive.

Statement 11: The method of statement 1 further comprising identifying acement additive comprising two or more of the inorganic particles, andestimating reactivity of the cement additive.

Statement 12: The method of statement 1 further comprising identifying acement additive comprising two or more of the inorganic particles,preparing a sample cement composition comprising the cement additive,testing the cement composition to determine one or more performancecharacteristics.

Statement 13: The method of statement 1 further comprising identifying acement additive comprising two or more of the inorganic particles, basedat least partially, on the correlations.

Statement 14: The method of any preceding statement further comprisingmixing a wellbore treatment fluid comprising at least one of theinorganic particles using mixing equipment.

Statement 15: The method of statement 14 further comprising introducingthe wellbore treatment fluid into a wellbore using one or more pumps.

Statement 16: A system comprising: a plurality of inorganic particles;an analytical instrument configured to gather physical and/or chemicaldata about the inorganic particles; a computer system configured toaccept the physical and/or chemical data and/or generate correlationsbetween properties of the inorganic particles based on the data.

Statement 17: The system of statement 16 wherein at least one of theinorganic particles comprises at least one of silica, alumina, iron,iron oxide, calcium, calcium oxide, sodium, potassium, magnesium,sulfur, and combinations thereof.

Statement 18: The system of statement 16 or statement 17 wherein theanalytical instrument is configured to perform one or more of functionsselected from the group consisting of microscopy, spectroscopy, x-raydiffraction, x-ray fluorescence, particle size analysis, waterrequirement analysis, scanning electron microscopy, energy-dispersiveX-ray spectroscopy, surface area, specific gravity analysis,thermogravimetric analysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio, API testing, and combinations thereof.

Statement 19: The system of any one or statements 16 to 18 wherein thecomputer system further comprises an algorithm configured to: analyzethe physical and/or chemical data and output a predictive model; andstore the predictive model in a predictive model database.

Statement 20: The system of statement 19 wherein the predictive modelincludes models of an effect other than a contribution to a cementitiousreaction.

Statement 21: The system of statement 19 wherein the predictive modelincludes a correlation of a specific surface area and water requirementof at least one of the inorganic particles.

Statement 22: A system comprising: a predictive model databasecomprising predictive model data, correlations between properties, andraw data; a materials database; a computer system configured to querythe predictive model database and the materials database and acceptinput from a user; and an algorithm capable of generating a calculatedcement composition.

Statement 23: The system of statement 22 wherein the algorithm isconfigured to improve the calculated cement composition by generating acement composition based on a cost objective of the calculated cementcomposition.

Statement 24: The system of statement 22 or 23 wherein the algorithm isconfigured to improve the calculated cement composition by selectingmaterials from the materials database.

Statement 25: The system of any one of statements 22 to 24 wherein thealgorithm is configured to: analyze the input from the user; analyze thedata from the predictive model database, the data comprising at least ofthe predictive model data, the correlations, and/or the raw data; andoutput the calculated cement composition

Examples of the methods of using the reactivity mapping technique willnow be described in more detail with reference to FIG. 3 . A system 300for analyzing the cement component is illustrated. The system 300 maycomprise a cement component sample 305, analytical instrument 310, andcomputer system 315. Cement component sample 305 may be any cementcomponent of interest. Cement components as previously described may begenerally categorized as alkali soluble. The cement component sample maybe placed or fed into analytical instrument 310. In some examples,analytical instrument 310 may be configured to automatically feed cementcomponent sample 305 into analytical instrument 310. Analyticalinstrument 310 may be configured to analyze the physical and chemicalproperties of cement component sample 305. As previously described,physical and chemical properties may comprise without limitation,morphology, chemical composition, water requirement, and others. Thedata generated by analytical instrument 310 may be sent to computersystem 315 for processing. Computer system 315 may comprise a processor,memory, internal storage, input and output means, network connectivitymeans, and/or other components common to computer systems. Computersystem 315 may take the data from analytical instrument 310 as input andstore it in the storage for later processing. Processing the data maycomprise inputting the data into algorithms which compute a result.Processing the data may also comprise organizing the data and mappingthe data as previously described. In particular, the computer system maycomprise algorithms configured to process the data to generate apredictive model of the physical and chemical behavior of cementcomponent sample 305. Predictive models may be stored in a predictivemodel database 320 which may be stored locally or on a network. Thepredictive model database 320 may comprise all previous predictivemodels generated by the algorithms as well as maps of the generated dataas well as the raw data.

Referring now to FIG. 4 , a system 400 for generating cementcompositions is illustrated. The system 400 may comprise a predictivemodel database 320 and computer system 410. In some examples, computersystem 410 may be the same computer system 315 of FIG. 3 . A user input420 may define engineering parameters such as the required compressivestrength of a cement slurry, the bottom hole static temperature of thewellbore, the required rheological properties of the slurry, thethickening time of the slurry, cement materials, cement additives, freefluid, permeability, pore pressure, fracture gradient, mud weight,density, acid resistance, salt tolerance, and other parameters. Computersystem 410 may be configured to input user input 420 and the predictivemodels, maps, and data stored in predictive model database 320 into apredictive cement algorithm. The predictive cement algorithm maygenerate a cement composition or compositions that meet the engineeringrequirements define by the user input 420. The output 430 of thepredictive cement algorithm may contain the relative amounts of eachcement component in the generated cement composition as well as thepredicted material properties of the cement composition.

For example, if a user selects Portland cement, fly ash, and volcanicrock as the cement materials available the computer system may querypredictive model database 320 for the required models, maps, and datacorresponding to the cement materials. As previously described, theremay be many different parameters such as particle size, regional sourceof the cement material, among others that may determine which set ofdata that is retrieved from predictive model database 320. Thepredictive cement algorithm may be configured to improve the outputcement slurry based on one or more parameters such as cost, compressivestrength, or any other chosen parameter. In some examples the predictivecement algorithm may optimize on two or more variable. Optimize in thiscontext should not be understood as arriving at a best result but ratherthat the cement algorithm is configured to iterate on one or morevariables. The output of the algorithm in this example may be forexample, 30% Portland by weight, 30% volcanic rock by weight, 20% flyash, and 20% lime, with a 120% excess by weight of water. The generatedslurry may conform within a margin of error to the engineeringparameters supplied by user input 420. The generated slurry may be addedto predictive model database 320 to be used in future calculations.

As previously discussed, the cement components may have secondaryeffects such as gelling, dispersive properties, heat generation, andother secondary effects previously mentioned in addition to the primaryeffect of being cementitious when included in a cement composition. Thesecondary effects may be beneficial as well. For example, if a cementcomposition requires a thickening agent, instead of using a separateadditive to thicken the cement composition, a cement component that gelsmay be used in the place of another additive. Other secondary effectsmay also be taken advantage of in a similar manner. The predictivecement algorithm may calculate the secondary effects of each componentin the cement slurry and adjust the relative amounts of each componentto ensure the target parameters are met. User input 420 may specify, forexample, a relatively higher free water requirement for the cementslurry. The predictive cement algorithm may choose to include a cementcomponent that requires less water based on the maps and data to ensurethat the free water requirement specified by user input 420 is met.

Reference is now made to FIG. 5 , illustrating use of a cementcomposition 500. Cement composition 500 may comprise any of thecomponents described herein. Cement composition 500 may be designed, forexample, using reactivity mapping as described herein. Turning now toFIG. 5 , the cement composition 500 may be placed into a subterraneanformation 505 in accordance with example systems, methods and cementcompositions. As illustrated, a wellbore 510 may be drilled into thesubterranean formation 505. While wellbore 510 is shown extendinggenerally vertically into the subterranean formation 505, the principlesdescribed herein are also applicable to wellbores that extend at anangle through the subterranean formation 505, such as horizontal andslanted wellbores. As illustrated, the wellbore 510 comprises walls 515.In the illustration, a surface casing 520 has been inserted into thewellbore 510. The surface casing 520 may be cemented to the walls 515 ofthe wellbore 510 by cement sheath 525. In the illustration, one or moreadditional conduits (e.g., intermediate casing, production casing,liners, etc.), shown here as casing 530 may also be disposed in thewellbore 510. As illustrated, there is a wellbore annulus 535 formedbetween the casing 530 and the walls 515 of the wellbore 510 and/or thesurface casing 520. One or more centralizers 540 may be attached to thecasing 530, for example, to centralize the casing 530 in the wellbore510 prior to and during the cementing operation.

With continued reference to FIG. 5 , the cement composition 500 may bepumped down the interior of the casing 530. The cement composition 500may be allowed to flow down the interior of the casing 530 through thecasing shoe 545 at the bottom of the casing 530 and up around the casing530 into the wellbore annulus 535. The cement composition 500 may beallowed to set in the wellbore annulus 535, for example, to form acement sheath that supports and positions the casing 530 in the wellbore510. While not illustrated, other techniques may also be utilized forintroduction of the cement composition 500. By way of example, reversecirculation techniques may be used that include introducing the cementcomposition 500 into the subterranean formation 505 by way of thewellbore annulus 535 instead of through the casing 530. As it isintroduced, the cement composition 500 may displace other fluids 550,such as drilling fluids and/or spacer fluids that may be present in theinterior of the casing 530 and/or the wellbore annulus 535. While notillustrated, at least a portion of the displaced fluids 550 may exit thewellbore annulus 535 via a flow line and be deposited, for example, inone or more retention pits. A bottom plug 355 may be introduced into thewellbore 510 ahead of the cement composition 500, for example, toseparate the cement composition 500 from the fluids 550 that may beinside the casing 530 prior to cementing. After the bottom plug 555reaches the landing collar 580, a diaphragm or other suitable deviceshould rupture to allow the cement composition 500 through the bottomplug 555. The bottom plug 555 is shown on the landing collar 580. In theillustration, a top plug 560 may be introduced into the wellbore 510behind the cement composition 500. The top plug 360 may separate thecement composition 500 from a displacement fluid 565 and also push thecement composition 500 through the bottom plug 555.

The disclosed cement compositions and associated methods may directly orindirectly affect any pumping systems, which representatively includesany conduits, pipelines, trucks, tubulars, and/or pipes which may becoupled to the pump and/or any pumping systems and may be used tofluidically convey the cement compositions downhole, any pumps,compressors, or motors (e.g., topside or downhole) used to drive thecement compositions into motion, any valves or related joints used toregulate the pressure or flow rate of the cement compositions, and anysensors (i.e., pressure, temperature, flow rate, etc.), gauges, and/orcombinations thereof, and the like. The cement compositions may alsodirectly or indirectly affect any mixing hoppers and retention pits andtheir assorted variations.

It should be understood that the compositions and methods are describedin terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps.Moreover, the indefinite articles “a” or “an,” as used in the claims,are defined herein to mean one or more than one of the element that itintroduces.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as, rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited, in the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range are specifically disclosed. Inparticular, every range of values (of the form, “from about a to aboutb,” or, equivalently, “from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to setforth every number and range encompassed within the broader range ofvalues even if not explicitly recited. Thus, every point or individualvalue may serve as its own lower or upper limit combined with any otherpoint or individual value or any other lower or upper limit, to recite arange not explicitly recited.

Therefore, the present disclosure is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular examples disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Although individual examples arediscussed, the invention covers all combinations of all those examples.Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below.Also, the terms in the claims have their plain, ordinary meaning unlessotherwise explicitly and clearly defined by the patentee. It istherefore evident that the particular illustrative examples disclosedabove may be altered or modified and all such variations are consideredwithin the scope and spirit of the present invention. If there is anyconflict in the usages of a word or term in this specification and oneor more patent(s) or other documents that may be incorporated herein byreference, the definitions that are consistent with this specificationshould be adopted.

What is claimed is:
 1. A method comprising: measuring properties of eachof a group of inorganic particles to generate data about physical and/orchemical properties of the inorganic particles; and analyzing the data,wherein the analyzing comprises generating correlations between themeasured properties of the inorganic particles based on the data andcategorizing the inorganic particles according to either the measuredproperties and/or to properties estimated by the correlations, whereinthe correlations comprise at least a water requirement as a function ofspecific surface area, wherein the water requirement is determined by aprocess comprising: preparing a blender with a specified amount ofwater; agitating the water at a specified rate; adding a powdered solidcomprising one or more of the inorganic particles to the water until aspecified consistency is obtained; and calculating the water requirementbased on a ratio of the amount of water to an amount of the powderedsolid required to reach the specified consistency.
 2. The method ofclaim 1 further comprising generating a statistical table comprising twoor more different parameters of the inorganic particles.
 3. The methodof claim 1 further comprising preparing a cement composition comprisingthe inorganic particles and allowing the cement composition to set in awellbore.
 4. The method of claim 1 wherein at least one of the inorganicparticles comprises at least one of silica, alumina, iron, iron oxide,calcium, calcium oxide, sodium, potassium, magnesium, sulfur, andcombinations thereof.
 5. The method of claim 1 wherein the measuringproperties of the inorganic particles comprises analysis by at least onetechniques selected from the group consisting of x-ray diffraction,x-ray fluorescence, scanning electron microscopy, energy dispersivespectroscopy, thermogravimetric analysis, and any combinations thereof.6. The method of claim 1 wherein the data comprises an amount of atleast one component selected from the group consisting of silica,alumina, iron, calcium, sodium, potassium, magnesium, sulfur, oxidesthereof, and combinations thereof.
 7. The method of claim 1 wherein thedata comprises average particle size, particle size distribution, andmorphology for each of the inorganic particles.
 8. The method of claim 1further comprising identifying a cement additive comprising two or moreof the inorganic particles and predicting one or more mechanicalproperties of a cement composition comprising the cement additive. 9.The method of claim 1 further comprising identifying a cement additivecomprising two or more of the inorganic particles and estimatingreactivity of the cement additive.
 10. The method of claim 1 furthercomprising identifying a cement additive comprising two or more of theinorganic particles, preparing a sample cement composition comprisingthe cement additive, testing the cement composition to determine one ormore performance characteristics.
 11. The method of claim 1 furthercomprising identifying a cement additive comprising two or more of theinorganic particles, based at least partially, on the correlations. 12.The method of claim 1, wherein the group of inorganic particlescomprises volcanic rock.
 13. The method of claim 1, wherein the group ofinorganic particles comprises a metal silicate.
 14. The method of claim1, wherein the inorganic particles are further categorized by silicacontent, calcium oxide content, alumina content, and by at least oneother oxide content, wherein the other oxide content is determined froman oxide analysis performed using an analytical instrument.
 15. A methodcomprising: measuring properties of each of a group of inorganicparticles to generate data about physical and/or chemical properties ofthe inorganic particles, wherein the data comprises average particlesize, particle size distribution, and morphology for each of theinorganic particles, and wherein the morphology comprises at least onevalue or description corresponding to either the sphericity, roundness,or general shape of the inorganic particles; and analyzing the data,wherein the analyzing comprises generating correlations between themeasured properties of the inorganic particles based on the data andcategorizing the inorganic particles according to either the measuredproperties or to properties estimated by the correlations, wherein thecorrelations comprise at least a water requirement as a function ofspecific surface area, wherein the water requirement is determined by aprocess comprising: preparing a blender with a specified amount ofwater; agitating the water at a specified rate; adding a powdered solidcomprising one or more of the inorganic particles to the water until aspecified consistency is obtained; and calculating the water requirementbased on a ratio of the amount of water to an amount of the powderedsolid required to reach the specified consistency.
 16. The method ofclaim 15, further comprising providing an estimate of a performancecharacteristic wherein the estimated performance characteristic iseither material reactivity, fluid loss control ability, or dispersingability.
 17. The method of claim 16, wherein the measuring comprisesperforming at least one measurement technique selected from the listconsisting of particle size analysis, specific gravity analysis,specific surface area analysis, compressive strength analysis,morphology analysis, and water requirement analysis.
 18. A methodcomprising: measuring one or more physicochemical properties of eachspecies of a group of inorganic particles to generate physical and/orchemical data about the inorganic particles; measuring one or morephysicochemical properties of a waste material to generate physicaland/or chemical data about the waste material; analyzing the data,wherein the analyzing comprises generating correlations betweenvariables and categorizing the inorganic particles and waste materialaccording to the variables, wherein the variables comprise one or moremeasured properties and one or more properties estimated by thecorrelations, wherein the correlations comprise at least a waterrequirement as a function of specific surface area, wherein the waterrequirement is determined by a process comprising: preparing a blenderwith a specified amount of water; agitating the water at a specifiedrate; adding a powdered solid to the water until a specified consistencyis obtained; and calculating the requirement based on a ratio of theamount of water to an amount of the powdered solid required to reach thespecified consistency; querying a predictive model database to retrievea predictive model, wherein the querying is based at least in part on auser input engineering parameter, wherein the predictive model is basedon an iterating on two or more of the variables, and wherein thepredictive model accounts for a secondary effect of the inorganicparticles; and outputting relative amounts of each cement component in acement slurry comprising a plurality of cement components based at leastin part on an output of the predictive model, wherein at least one ofthe cement components comprises one or more of the inorganic particles;and predicting a performance characteristic of a cement based, at leastpartially, on the output of the predictive model and the measured orestimated properties, wherein the cement comprises the waste materialand one or more of the inorganic particles.
 19. The method of claim 18,wherein the performance characteristic comprises at least one mechanicalproperty selected from the group consisting of compressive strength,tensile strength, Young's modulus of elasticity, and any combinationthereof.
 20. The method of claim 18 wherein the measuring comprisesperforming at least one measurement technique selected from the listconsisting of specific surface area analysis, morphology analysis, waterrequirement analysis, specific gravity analysis, thermogravimetricproperties analysis, particle shape analysis, particle size analysis,particle size distribution analysis, dispersing ability analysis,thickening time analysis, 24 hour compressive strength analysis, fluidloss analysis, and any combination thereof.
 21. The method of claim 18,further comprising specifying a desired performance characteristic ofthe cement and selecting one or more cementitious components based, atleast in part, on the predicted performance characteristic, wherein thecement additionally comprises the one or more cementitious components.22. The method of claim 18, wherein the performance characteristiccomprises at least one property selected from the list consisting ofslurry density, average specific gravity, pressure, curing age, waterrequirement, dispersing ability, thickening time, reactivity, heatgeneration, and any combination or derivative thereof.
 23. The method ofclaim 18, wherein the secondary effect of the cement component isgelling.
 24. The method of claim 18, wherein the secondary effect of thecement component is dispersing ability.
 25. The method of claim 18,wherein the user input engineering parameter is a gelling rate.